Please go to \hyperlink{ieee_8finc}{api/ieee.\+finc} for the A\+P\+I documentation. interaction between the Fortran run time settings and C may lead to unreliable behaviour; for example, setting of I\+E\+E\+E rounding apparently does not always work correctly. Within Fortran, usage of the facilities defined in the intrinsic I\+E\+E\+E modules is the reliable and therefore appropriate method. 